Huawei Quidway S6500 Series Operation Manual page 172

Operation Manual - Routing Protocol
Quidway S6500 Series Ethernet Switches
to take changes. Hence, the network will always in "turbulence", and a great number of
OSPF packets will be generated and transmitted in the network. This will lower the
network bandwidth utility. In addition, each change will cause all the routes on the
network to recompute the route.
OSPF solves the above problem by partition an AS into different areas. Areas logically
group the routers. The borders of areas are formed by routers. Thus, some routers may
belong to different areas. A router connects the backbone area and a non-backbone
area is called Area Border Router (ABR). An ABR can connect to the backbone area
physically or logically.
IV. Backbone area and virtual link
Backbone Area
After the area division of OSPF, not all the areas are equal. In which, an area is different
from all the other areas. Its area-id is 0 and it is usually called the backbone area.
Virtual link
Since all the areas should be connected to the backbone area, virtual link is adopted so
that the physically separated areas can still maintain the logic connectivity to the
backbone area.
V. Route summary
AS is divided into different areas that are interconnected via OSPF ABRs. The routing
information between areas can be reduced through route summary. Thus, the size of
routing table can be reduced and the calculation speed of the router can be improved.
After calculating an intra-area route of an area, the ABR summarizes multiple OSPF
routes into an LSA and sends it outside the area according to the configuration of
summary.
4.2 OSPF Configuration
In various configurations, you must first enable OSPF, specify the interface and area ID
before configuring other functions. But the configuration of the functions related to the
interface is not restricted by whether the OSPF is enabled or not. It should be noted that
after OSPF is disabled, the OSPF-related interface parameters also become invalid.
OSPF configuration includes:
Enabling OSPF and Entering the OSPF View
Entering OSPF Area View
Specifying Interface
Configuring Router ID
Configuring the Network Type on an OSPF Interface
Huawei Technologies Proprietary
4-4
Chapter 4 OSPF Configuration